Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a non-transitory computer-readable medium and, more particularly, to image processing of controlling the applied amount of a color material.
Description of the Related Art
An image forming apparatus generates pixel information from print data and forms an image while controlling the toner amount based on an image signal generated based on the pixel information. If the amount of toner applied at the time of development of image formation is large, that is, the toner applied amount is large, the toner may be not completely fixed and spatter, or come off concerning portions of high dot density. These problems arise at different frequencies depending on the environment where the image processing apparatus is placed (ambient conditions such as the humidity and temperature) and the printing medium type such as paper or sheet.
When printing a straight line in the main-scanning direction, toner may spatter backward in the sub-scanning direction of a line 202 printed on a transfer material (printing medium) 201 and disturb the image, as shown in FIG. 2. This will be described with reference to FIG. 3. When passing through a fixing unit 301 incorporating a heater of high temperature, the transfer material 201 is suddenly heated, and water in it changes to steam 302 and comes out. At this time, if toner 303 is applied thin and high, it is overwhelmed by the steam 302 from the transfer material 201 and blown off backward in the conveyance direction. The phenomenon that the toner spatters and disturbs the image will be referred to as a “tailing-blur phenomenon”.
A conventional measure against the tailing-blur phenomenon is to decrease the toner applied amount. More specifically, toner is thinned with respect to dots of image data subjected to image formation. For the conventional method, however, a problem of degradation in image quality has been pointed out. In particular, the degree of tailing-blur phenomenon changes depending on the ambient conditions or printing medium type. Hence, when the toner thinning rate is raised in accordance with the degree of tailing-blur phenomenon until it is completely eliminated, the image degrades due to thinning of lines, a decrease in the density, or missing of an image. To prevent this, there is proposed a method of executing thinning processing only for a line width to cause the tailing-blur phenomenon and suppressing the thinning amount not to make image degradation unnoticeable (for example, see Japanese Patent Laid-Open No. 2001-80112).
In this related art, however, since the thinning method is decided based on only line width information without considering the state around the line, unprinted portions may be noticeable due to image loss caused by thinning if a density of an area around the line is dark.